Pressure sensitive switch



Nov. 19, 1957 r L. B. COURTOT PRESSURE SENSITIVE SWITCH Filed Jan. 24,1956 IN VEN TOR. 100/5 3- Col/R707 A f l n w L ans--- a. g 4 m w i4 r/If. 4 1 4 4 a 4 a Aw/ m z L J m -M.

w w W M R My 7 m #0 7 WM 2 PRESSURE SENSITIVE SWITCH Louis B. Courtot,Cleveland, Ohio, assignor to The Weatherhead Company, Cleveland, Ohio, acorporation of Ohio Application January 24, 1956, Serial No. 561,047 2Claims. (Cl. 200-83) This invention relates to a switch deviceresponsive to the application of fluid pressure to make a contactbetween spaced electrical terminals for the completion of an electricalcircuit.

It is an object of my invention to provide an improved pressureresponsive switch of simplified construction.

It is a further object of my invention to provide a resilient diaphragmmeans on which is mounted a metallic surface for completing anelectrical circuit.

It is an object of my invention to provide a simplified fluid pressureswitch which can be readily used in a hydraulic braking system of anautomobile so that the application of fluid pressure acts upon aresilient diaphragm means to close the switch, and the release of fluidpressure allows the diaphragm to restore itself to its initial positionthereby opening said switch.

It is a further object of my invention to provide a novel securementmeans for the diaphragm means of a fluid pressure switch.

It is an object of my invention to provide an electrical conductingmeans suitably mounted on a self-restoring diaphragm means wherein theelectrical conducting means is caused to make contact with the switchterminal upon application of fluid pressure, and upon release of saidfluid pressure the self-restoring diaphragm means moves the electricalconducting means away from said switch terminals.

These and other objects and advantages will appear from the followingdescription relating to the drawings of which:

Fig. l is a sectional elevation of the pressure switch device;

Fig. 2 is a sectional view taken at 2-2 of Fig. 1;

Fig. 3 is a sectional elevation showing the pressure switch of Fig. 1 incontact position;

Fig. 4 is a partial section of the diaphragm arrangement beforesecurement;

Fig. 5 is a modified form of a pressure switch shown in section; and

Fig. 6 is the pressure switch of Fig. 5 shown in contact position.

Referring to Fig. 1, a round metal body 10 is provided with an annularrecess 11 communicating with a passageway 12. Said passageway 12 islocated in a threaded stem portion 12a of body 10 and is adapted tocommunicate fluid pressure to recess 11 from a pressure system notshown. Located within body 10 is a block 13 of rigid electricalinsulating material such as a phenolic resin. Molded within block 13 aretwo electrical terminals 14 and 15 which are provided with plug-typeprojecting ends at one end, with the other end of the terminalsextending into a block recess 16.

A diaphragm 17 of molded synthetic rubber-like material which is notadversely ailected by hydraulic fluid is secured between block 13 and anannular inclined recess 11a of body 10.

Fig- 4 discloses the diaphragm 17 with peripheral rib atent PatentedNov. 19, 1957 ICC 18 resting on the annular inclined recess 11a prior toassembly of block 13 and body 10. When block 13 is inserted into body 10and flanges 10a are crimped into shoulder groove 13a to hold block 13 inposition, the peripheral rib 18 is biased outwardly along the incline ofgroove 11a. This action at the peripheral rib 18 is shown in Figs. 1 and3, and eliminates the formation of a wrinkle or the fold forming at thereduced radially inward portion of the diaphragm 17 by placing this areaunder a slight tension in the non-pressurized state. Such wrinklingwould aflect the life of the diaphragm and make it more difiicult toobtain prescribed characteristics from the diaphragm when subjected tofluid pressures.

Diaphragm 17 formed to provide peripheral rib 18 is also formed toprovide a central stem portion 19 extending normal to the diaphragm andproportioned axially to normally bear against the insulating block 13 ata central recess 13b. Surrounding stem 19 and in flat contact withdiaphragm 17 is an annular metal disc 20 which is snapped on stem 19 andmay be secured thereto by seating in an annular groove on the base ofthe stem. The disc 20 is arranged to be positioned toward and away fromterminals 14 and 15 by the fluid pressure actuation of diaphragm 17, andwhen so contacting said terminals the switch is in the closed position.

In operation, body 10 is placed in communication through passage 12 witha hydraulic fluid system such as for example might be utilized in anautomobile braking system. The hydraulic fluid pressure is eifectivewhen the brake is applied to move the diaphragm 17 t0 the position shownin Fig. 3. The movement of the diaphragm 17 in response to fluidpressure upsets the stem 19 so that it nearly fills the recess 13b ofinsulating block 13. The shortening of the stem 19 by the diaphragmmovement causes the annular metal disc 20 to contact the electricalterminals 14 and 15 to close the circuit through the switch. Upon therelease of fluid pressure from chamber 11, the diaphragm 17 is restoredto its original position by the resiliency in the stem portion 19 and inthe body of the diaphragm.

Fig. 5 is a modification of the pressure switch wherein the body 23surrounds rigid insulating block 24 of phenolic resin with electricalterminals 25 and 26 molded therein.

Body flanges 23a are crimped over shoulder 24a of block 24 to secure adiaphragm 27 at its periphery between 23 and block 24.

A passageway 28 is formed in the body communicating with the one sideor" a diaphragm 27 for the application of fluid pressure to thediaphragm. Diaphragm 27 is shown provided with a central portion 29extending normal thereto and having a rounded end disposed in a recess39 in the block 24. A cylindrical chamber 31 is shown in block 24 toaccommodate the expansion of a central stem portion 29. An annular metaldisc 32 is snap-fitted on that side of diaphragm 27 adjacent theterminals 25 and 26 and is maintained in position on the diaphragm by anannular ridge 33 on central stem portion 29.

The electrical terminals 25 and 26 extend into recess 24b, in which thediaphragm 27 is allowed to move when actuated by fluid pressure inchamber 23b.

A reinforcing disc 34 of a rigid plastic or metal is molded in thediaphragm to assist in resisting extrusion of the diaphragm through thecentral hole in disc 32 and maintaining alignment of disc 32 forsimultaneous contact with terminals 25 and 26.

When fluid pressure is introduced through passageway 28, the diaphragmis moved thereby to the position shown in Fig. 5 whereby the annularmetallic disc 32 makes electrical contact with terminals 25 and 26 inrecess 24b to close the switch. The central portion 29 is axiallycompressed and radially expanded by the movement of the diaphragm inresponse to fluid pressure. When fluid pressure is reduced at passage 28the pressure induced stress in the central stem portion 29 will restorethe diaphragm to its unstressed or normal condition and thus move thediaphragm 27 away from the electrical ter? minals 25 and 26 breaking thecontact between the terminals and annular metallic disc 32.

Thus I have disclosed and described a fluid pressure switch having onlya minimum of parts, and having a diaphragm switch actuating means whichreturns to its original position upon removal of the application offluid pressure. Such switch presents a simplified direct actingconstruction that aflords positive closure upon application of fluidpressure. Such switch presents a simplified direct acting constructionthat aflords positive closure upon application of fluid pressure andpositive opening from the resiliency of the diaphragm upon removal offluid pressure from the diaphragm.

While preferred embodiments of the invention have been described inconsiderable detail, it will be understood that modifications andrearrangements of the parts may be resorted to without departing fromthe scope of the invention as defined in the following claims.

What is claimed is;

1. A fluid pressure switch comprising a metal cup having a fluid openingin the bottom thereof, a flexible rubher-like diaphragm over saidopening and an integrally molded cylindrical stern extending from thediaphragm on that side or the diap r m y rom said ope i a metal dischaving a central aperture, said central aperture having a diameter lessthan the diameter of said cylindrical stem and said disc being retainedon said stem at the juncture of the stem with the diaphragm by beingpressed over the cylindrical stem, a melded cylindrical plug ofinsulating material having a diameter corresponding to the innerdiameter of the cup, said plug being disposed in said cup to press thediaphragm against the bottom of the cup at its periphery, said plugbeing retained within the cup by having the open end of the cup bentinwardly over the plug and a pair of spaced electric terminals molded insaid cup with the inner ends of said terminals disposed at either sideof said diaphragm stem and adjacent said apertured metal disc, saidinsulating plug adjacent the diaphragm having a central opening slightlylarger than the cylindrical stem of the diaphragm to receive said stemand limit its deformation when the disc on the diaphragm is moved intocontact with said terminals by fluid pressure.

2. A fluid pressure switch comprising a metal cup having a fluid openingin the bottom thereof, a flexible rubber-like diaphragm over saidopening and an integrally molded cylindrical stem extending from thediaphragm on that side of the diaphragm away from said opening, a metaldisc having a central aperture, said central aperture h ving a diameterle s th n the diameter of said cylindrical stem and said disc beingretained on said stem at the juncture of the stem with the diaphragm bybeing pressed over the cylindrical stern, a molded cylindrical plug ofinsulating material having a diameter corresponding to the n r diame erof th cup, s id plug b ng h p s d in aid cap to pres th aph a m a a st.the t m of he up at its P r p e y, sa plug ein tained within the cup byhaving the open end of the up bent i ardly over the p ug and a Pai atspac tric, erminal molded in said cup with the inner ends of id terminald sp sed at eit er side of sa d iaph a stem and adjacent s id ap u ed.metal disc, said in Sulating P adj cent th diaphra m having a centralcylindrical opening larger in diamet than th diameter of h y in r alstem of th diap ragm o receive said stem and limit the deformation ofthe stern when the di c n the ph gm is n Contac wi h said terminals-References Cited in the file of this patent UNITED STATES PATENTS1,840,340 White Jan. 12, 1 932 2,307,066 Paulus Jan. 5, 1943 2,337,809Gaynor Dec. 28, 1943 2,462,189 Hess Feb. 22, 1949 2,744,543 Brady May 8,1956 2,765,751 Osius Oct. 9, 1956 2,766,350 Gres et al. v Oct. 9, 19 56,

F R GN PA E 876,771 Germany May 18, 1953

